Kube Container Exec

Summary

This is a small command line tool to basically make kubectl get pods and kubectl exec combined and usable in kubernetes.

One of the main purposes is using Kubernetes Jobs and CronJobs and use this tool to execute jobs in existings (Pet-) Pods.

Sometimes it is not feasible to run the Job as a new Pod, so this tool uses a very small Pod that talks to the Kubernetes API to run the actual Job as a new process in the specified container.

Usage

The tool is configurable via both environment-variables and command line flags.

./exec-linux [flags] command -flag1 -flagFoo=bar

The first flags are described below. Everything which comes later is passed to the command(s).

The command is not run in a shell, as there are containers which do not have a shell. If you want a shell you have to invoke it yourself, e.g.

./exec-linux /bin/bash -c 'ps aux && free -m && w'

Environment Variables

• KUBECONFIG: specify the path to a Kubernetes config file. By default there should be sufficient self-configuration possibilities, including in-cluster self-configuration.
• CONTAINER: specify the container in which the process should be started.
• FILTER: specify which filter should be used to find a pod, e.g. app=mytool.

Command Line Flags (excerpt)

• -v: Verbosity level, 4 includes exec-specific output, 6 includes basic kubernetes debug, 8 includes REST-api debugging.
• -container: Set the container, overrides the CONTAINER environment variable
• -filter: Set the filter, overrides the FILTER environment variable
• -kubeconfig: Set the path to kubeconfig. Overrides the KUBECONFIG variable.